Fire-retarding board



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July 22, 1958 Filed Deo. 28, 1955v 32 24 l .as

July 22, 1958 J. c. 4srfln'KERv v FIRE-RETARDING BOARD Filed Dec. 2a, 195s '3 Sheets-Sheet 2 'JMJ/2 f la 46 l 24 5 v k :t D 1- ,32

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July 22, 1958 J. c. sNrrKER 2,844,501

' FIRE-RETARDING BOARD Filed Dec. 28, 195s Y s sheets-sheet s IN V EN TOR.

Finn-Ratiatum@ BOARD Jens C. Snitker, Riisskov, Denmark, assignor of one-half to Soren Clausen, Aarhus, Denmark Application December 28, 1953, Serial No. @9,594

Claims priority, application Denmark December 30, 1952 1 Claim. (Cl. 154-44) The invention relates to a lire-retarding board, which consists mainly of combustible material, preferably wooden material, with incombustible material inlaid.

The board is intended for use in the building industry to provide partitions, wall covering, and doors, but it is mainly intended for use in ships, notably passengercarrying ships, as lire-resisting bulkhead, known as the B-class bulkhead, which is designed to prevent iiames from spreading rapidly, if a fire arises. For such use the board according to the present invention may constitute the B-class bulkhead itself or part thereof, and it may also constitute the material, of which doors or hatches in the bulkhead are manufactured.

The object of the invention is to provide a tire-retarding board, which mainly consists of wood or wooden material, but nevertheless can prevent tire from penetrating through the board, at any rate for a certain length of time.

Another object is to provide a board which can be used in the same way as ordinary boards of furniture plywood and worked upon and shaped by conventional tools and machinery.

A further object is to provide a board of the kind in question, which will be strong and durable even under varying conditions as to moisture and heat.

With the above and other objects in View the present invention consists in the combination and arrangement of parts, hereinafter more fully described, illustrated in the accompanying drawings and more specifically pointed out in the claims, it being understood that changes may be made in the form, size, proportions, and details of construction without departing from, or sacrificing any of the advantages of the invention.

In the drawings Fig. 1 is a side-view of one embodiment,

Figs. 2 and 3 are cross-sections of the same embodiment, on the lines il-ll and Ill-lil, respectively, in Fig. l,

Fig. 4 is a side-view of a second embodiment,

Fig. 5 is a perspective view of one corner of the embodiment shown in Fig. 4,

Fig. 6 is a cross-section of the embodiment shown in Figs. 4 and 5,

Fig. 7 is a third embodiment, in perspective, and

Fig. 8 is part of a wooden slat for this embodiment, also in perspective.

in the embodiment shown in Figs. 1-3, the fire-retarding board consists of three wooden layers 10, 12 and 14. On the layer 10, square projections 16 are provided at one side face, which projections are mutually interspaced on a regular pattern, as will be seen in Fig. 1, where said projections are shown dotted. On the layer 14, similar projections 13 are provided according to the same pattern, and are shown in dot-and-dash line in Fig. l. When the layers and 14 are placed side by side with that face uppermost on which the projections 16 and 18 are provided, the patterns formed by the projections on the two layers will be perfectly congruent, but when I 2,344,501' Patented July 22, 1958 the layers 10 and 14 are placed with said faces towards each other, the projections 18 will be seen to be evenly distributed between the projections 16, as appears from Fig. 1.

The layers 10 and 14 may be made of a wooden sheet, in one side face of which cross-way grooves are cut, so that the aforesaid projections appear. The said layers, however, may also be constructed of an ordinary wooden sheet with plane-parallel side faces, to one of which there are glued low wooden blocks, which constitute the projections. In this case it is 'suitable that all blocks should have the same direction of fibre as the underlying sheet.

The layer 12 is a simple sheet with plane-parallel side faces.

Before the three layers 10, 12 and 14 are assembled, a layer of incombustible material 20 has to be provided on the 'sides of the two outer layers 10 and 14, which carry theprojections 16 and 18. This layer 20 must be of the same thickness as the projections, so that the latter penetrate the layer.

The incombustible material is suitably made up of asbestos. lt may, for example, be formed of an asbestes sheet, in which square apertures are punched to correspond to the projections. The said sheet 20 is glued tothe corresponding outer layer in such a way that the projections extend through the apertures in the sheet. It is also possible first to glue the asbestos sheet to the plane side face of the outer layer and thereupon to insert the blocks, which are to constitute the projections, in the apertures in the asbestos sheet, at the same time glueing them to the outer layer.

Another method of producing the layer of incombustible material is to use a pulp of asbestos libre, the fluid component of which is water-glass. The pulp is spread over the side of the outer layer, on which the projections are provided, and the excess pulp is stripped off by moving a bar over the projections, so that the layer thickness becomes exactly equal to the height of the projections. The water-glass acts as a weak, yet sufiicient, binding agent between the asbestos fibres themselves and between the libres and the wood. After a suitable drying the three layers 10, 12 and 14 are glued together, e. g., with a synthetic resin glue, and the compound board is inserted in a glue press, where it remains for a `suitable period.

Besides asbestos, other tireresistant substances may be used as incombustible material, e. g., inorganic substances, preferably of mineral origin, such as mica. It is expedient that the substance should be of a brous or laminated nature, so that good cohesion is imparted to its component parts when pressed, possibly in the presence of a `suitable binding agent, such as Waterglass. Furthermore, a fire-resistant substance with good thermal insulation properties is preferred. l

ln order to avoid bending and warp in the compound board, it is expedient that the direction of fibre in the layer 12 lforms an angle, e. g., a right angle, with the direction of fibre in the layers 10 and 14, which preferably have the same direction of libre. The layer 12 will then act as an arresting layer. Furthermore, thin wooden sheets 22 may be glued to either side of the compound board, the fibre directions of which coincide with that of the layer 12, and thus also act as arresting layers.

The board heretofore described possesses the quality that Wood is glued to wood in the process of assembling the individual layers, thus effecting a high degree of cohesion between these layers with the result that the compound board is comparable to ordinary boards of furniture plywood and can be used as such. Furthermore, an arbitrary line across the board will always cut through at least one layer of the incombustible material,

3 even if the line forms a considerable angle with the perpendicular to the board, see e. g. the line a-a in Fig. 2. This means that radiant heat, which is the most dangerous factor in a ytire, when part of the board has been burnt away, will always hit incombustible material and thereby be retarded or prevented from igniting the wooden material behind it, so that a complete burning through of the compound board will be prevented or at any rate delayed for a considerable time. This is of paramount importance in the case of lire in buildings and ships, in which wood is used for partitions, doors, and the like.

The embodiment shown in Figs. 4 and 5 is constructed of two wooden layers 24 and 26, in one side face of which there are provided wide grooves 28 and 30, respectively, which are illed with incombustible material, e. g. strips 32 and 34, respectively, which are cut from asbestos sheet. Between the grooves in each sheet there are provided narrow ribs 36 and 38, respectively. The two wooden layers 24 and 26 with the asbestos-filled grooves 28 and 30 are placed against an intermediate wooden layer 40 and connected thereto, preferably by glueing, in such a way that the ribs of the outermost layers are displaced in relation to each other.

It is to be preferred that the grooves 28 and 30 in the layers 24 and 26, respectively, are low and that the intermediate layer 40y is thin. Hereby, radiant heat, which penetrates a rib 36 or 38 as obliquely as possible in relation to 'the normal on the board, will always hit the incornbustible material formed by the asbestos strip 32 or 34 in the opposite outer layer. This can be seen in Fig. 6 at the line b-b.

In the embodiment shown in Figs. 4 and 5, the layer 40 is designed as an arresting layer. The same applies to the sheets 42 and 44, which are glued to the outer sides of the compound board.

In order to obtain a board, which is not subject to expansion or contraction, the layers 24 and 26 are preferably constructed in the following Way:

A number of kiln-dried deal boards are glued together with the side surfaces toward each other in such a way that right faces right and wrong faces wrong. The block thus formed is cut up in the direction perpendicular to the glued side faces in sheets, which may have a thickness of, e. g., 9 millimetres. In one side face of these sheets there are cut grooves, e. g., 50 millimetres Wide and 1.5 mm. deep, the ydistance between each of which is 6 millimetres. In Figs. 4'and 5 the glue joints between the boards are denoted with the numeral 46.

According to Fig. 7 the board is constructed of wooden slats 48, which are glued together edge to edge. At its side edges each slat is provided with grooves of different depths. As will be seen from Fig. 8, a low groove is provided at the uppermost part of the left side edge of the slat and a deeper groove `S2 at the lowermost part. At the uppermost part of the right side edge there is provided a deep groove 54 and at the lowermost part a low groove 56. The grooves S0 and S4 are on the same plane, and the same 'applies to the grooves 52 and 56. Between the grooves 50 and 54 a narrow bridge 58 is provided in the wooden material, and between the grooves 52 and 56 there is another narrow bridge 60, which is displaced in relation to the former.

When the slats 48 are assembled as shown in Fig. 7, mutually displaced channels will be provided on two different planes. In the assembling process, iucombustible material, e. g., asbestos strips 62, is inserted in said channels. The strips 62 are suitably glued to the channels.

The groove arrangement described in the foregoing may be provided on more than two different planes, if so desired.

To the uppermost and lowermost sides of the resulting board, an arresting layer 64 may be glued and on top thereof a covering layer 66, the fibres of which preferably extend parallel tothe longitudinal direction of the slats 48.

When, in the process of assembling the board, the adjoining layers are placed as arresting layers in the way described heretofore, a board will be provided, which vhas the same strength and the same resistance to contraction and expansion as the known boards of furniture plywood. A

Having thus fully described my invention I claim as new and desire to secure by Letters Patent:

A fire-retarding board, consisting of slats of wooden material, having at their side edges grooves of different depths, so arranged that channels will be formed when the slats are joined edge to edge, said channels being so disposed on at least two different planes that the channels on one plane are displaced in relation to the channels on the other plane, said channels enclosing strips of asbestos.

References Cited in the le of this patent UNITED STATES PATENTS 1,987,506 Fitzpatrick Jan.l 8, 1935 2,065,045 Broback et al Dec. 22, 1936 2,401,281 Webb May 28, 1946 2,428,325 Collins Sept. 30, 1947 

